Improvement in dry-docks



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Leners Param No. 112,525, dated Marel 14, 1,871.

iMPRoi/EMENT IN DRY-oocKs.

'l'he Schedule` referred to 'in' these Letters Patentand parl: of lthe sanne.

To` auffwlwm )it may concern A 1 Beit knownV that I, GEORGE AfAL-BERTsoN, of

make and nselthe same,fr`eferenee being had. to the accmpanying drawing forming partei'` this specifica.-

r Figure lisa detaii `s'idefview of my improved drydock.` Y

Figure Zisan" end viewlof the same` "Similar Ietterswof reference indicate corresponding y parts. f

l Myinventin hasiforitsobjecttoimprovethe con-- structionfof dryU-"deksg so thatvessels *may be raised y outot andy-loweredintolthelwatergby"the yfall -andrise r "of the tide",and which shjallrat the saine time be simple in construction;l and f `Itcon'sistsn'nthe' construction-and combination lof `the various parts, iasf hereinafter moleully` described. r A representspiles, which are driven into the `ground shouldf` be driven closeetogether, and` lankaspiked;` to them `in the ordinary il Tel-,beside parts f the platform B are securelyat# tachedathejendsoffa s'nci'ent number; of chains, 4O,

i `whiclrpass overkpulieysDfpivoted to the upper ends y `of the `piles A501' tothe `st1`1ing piecesr connecting the t upper ends ofysaid `piles By this construction the platform B will move about twice as far as the oats F, from the-fact that the parts of the'chain G connected withthe platform B are single, whiley the parts 0f said chains connected with the ioats are dpuble. v As the tide rises the floats F will frise with it, and the platfdrm `B will'sink into thewater.

When the `platform B has sunk to the necessaryV depth, the vessel is iioated into the dock and into the 'proper .position above the piatform'B. As thetide falls the' oats F fall with it and raise thel platform B and the vessel out of the water. When the tide has fallen` to its lowest point the chains C are keyed so as to support the platform B and ,the vessel upon it at such a height above the water that the tide upon its rise will not touch them.

When the work upon the vessel has been completed the4 operation is reversed and the' platform B and the vesselV upon it are lowered into the water by the rise of, the tidefallowing the vessel to be loated off the said platform-the vessel being thus both raised out ,of and lowered into the water by the fall Aand rise of the tide. t

Havingztbus' described my invention, 4I` claimas new and desire -to secure by Letters Patent'- The combination of 'theplatform' lB, chains C, 'and heavy floats F witheach other and with the piles A,

Vforming the lsides of the dock, substantiallyias herein shownan'd described,l and for the purpose set forth.

` The above specification of my li'nventirnl signedby r me this 27th day of'Apr'il, 187

GEORGE A.' ALBERTSON.

Witnesses:

. WM. H. FERGUSON, l JAMES T. GRAHAM.' 

